Draft regulator for hot air



Oct. 14, 1941. Mt w T 2,258,729

DRAFT REGULATOR FOR HOT AIR FURNACES Filed March 6, 1941 lnuentcm Patented Oct. 14, 1941 gram OFFICE DRAFT REGULATOR FOR HOT AIR FURNACES Millard Whyte Best, Hamilton, Ontario, Canada Application March 6, 1941, Serial No. 381,928

Claims.

My invention relates to improvements in draft control devices for hot air furnaces and the object of the invention is to provide a device actuated by the flow of air passing into or through the furnace to be heated whereby the passage of a very simple device which can be readily installed onany standard type or hot air furnace and which is also furnished with a simple adjustment whereby its responsive movement to air velocity changes can be readily altered.

With the foregoing and other objects, in view as shall further appear, my invention consists of a draft control device formed and arranged all as hereinafter more particularly described and illustrated in the accompanying drawing, in

which,

Figure 1 is a front elevational view of a hot air furnace furnished with my device.

Figure 2 is a side elevational view of the furnace as illustrated in Figure 1.

Figure 3 is an enlarged perspective view of my device as attached to the outer ends of the check draft inlet pipe and the furnace draft inlet pipe, the lower portion of the device being contained within the air inlet conduit through which air is entering the furnace tobe heated, such conduit being shown broken away.

Figure 4 is a front elevational view of the upper portion of my device as attached to the check draft and furnace draft inlet pipes, and,

Figure 5 is a horizontal cross-sectionalview through a fragmentary portion of the air inlet conduit and showing the lower portion of my device contained therein,

Like characters of reference indicate corresponding parts in the different views of v the drawing.

In Figures 1 and 2 I show a standard hot air furnace, which comprises the usual central fire box I surrounded by a casing 2 to' form a chamber surrounding the fire box wherein the air is heated to pass therefrom through the hot air pipes 3. The furnace flue pipe 4 extends from the dome of the fire box through the side of the furnace casing 2, all of which construction follows general standard practice. 7

The furnace is furnished with a grate draft pipe 5 which extends from the ash pit 6 of the grate outwardly through the casing 2. A check draft inlet pipe 1 extends upwardly and opens into the flue pipe 4. Air to be heated is directed into the air chamber in the furnace through a conduit 8 opening into the bottom of the casing 2. In the standard furnace the passage of air into the grate is manually controlled by a damper as is also the passage of air through the flue pipe. In my present invention I provide a device whereby the grate draft and check draft dampers are synchronously actuated to a degree proportionately to the velocity of air passing into the fur nace chamber through the conduit 8.

As will be seen from the drawing, I provide an elbow at the bottom of the pipe 1 which has its open end extending in the same vertical plane as the open end of the pipe 5. The open ends of the pipes 5 and l, which are positioned one above the other, carry a substantially 8 shaped member 9'which surrounds the ends of the two pipes and is suitably secured thereto. A second substantially 8 shaped member ID is positioned to rest against the member 9. The lower rings of the members 9 and ID are provided with a pair of lugs ll having orifices therein and in which a bolt or pin I2 is contained. The opposite sides of the two lower rings are each furnished with a lug, the lower ring of the member 9 carrying a lug l3 and the lower ring of the member l0 carrying a lug [4. These lugs are so positioned upon their rings that they are normally spaced apart a slight distance.

A thumb-screw I5 is rotatably contained within the lug I4 and has its lower end threaded into an'orifice in the lug [3. While the unthreaded upper end of the thumb-screw I5 is freely rotatable within the lug I4, it is retained against vertical sliding movement in the lug [4 by a cross-pin l6 so that as the thumb-screw is rotated the lug i3 is either drawn towards or moved away from the lug l4, depending upon the direction in which the thumb-screw I5 is turned. It will thus be seen that when the thumb-screw I5 is rotated that the 8 shaped member I0 will move or swing relatively to the 8 shaped member 9 about the bolt or pin l2 in the lugs l I, as shown in Figure 4.

The 8 shaped member I0 is formed at its lower end with a. downwardly extending bracket ll formed with a foot [8. The bracket ll extends downwardly into the air conduit 8 and is positioned in close proximity to one of the side walls thereof and preferably extends downwardly to the vicinity of the bottom of the conduit. The 8 shaped member Ill and its bracket I! carry a spindle IS, the upper end of the spindle being pivoted in the upper end of the member Ill and the lower end of the spindle pivoted in the foot [8. In order to facilitate the insertion of the spindle [9, the central and lower portions of the member H] are formed with channels 20 through which the spindle I9 extends. I form the ends of the spindle IS with pivot points 2| which are contained within cups 22 threaded into the top of the member In and foot IB. In this manner a practically frictionless mounting for the spindle I9 is obtained.

The upper portion of the spindle l9 passing through the upper circular portion of the member l carries a damper disc 23 and the central portion of the spindle passing through the lower circular portion of the member ID carries a damper disc 24, the damper 24 being positioned substantially at right angles to the damper 23. The lower portion of the spindle extending downwardly to the foot I 8 carries a flap member 25 which is contained within the conduit 8. It is to be understood that the dampers 23 and 24 and the flap 25 are secured to the spindle I!) so that they move simultaneously.

The frame l and its contained spindle l9 are, at the time of installation, positioned at a slight inclination so that the flap 25 on the freely swingable spindle [9 will swing to a rest position across the air inlet conduit 8, as illustrated in full lines in Figure 5. When the flap 25 is in this position the damper disc 24 controlling the passage of air to the grate is swung fully open and the damper disc 23 in a position closing the entrance orifice to the pipe I. As soon as the furnace has been lit, air will be drawn into the grate past the open damper 24 through the pipe 5, and in due course the air in the air chamber in the furnace will be heated to pass outwardly through the pipes 3, and fresh cold air will pass into the furnace through the conduit 8. As soon as the fresh air commences to pass along the conduit 8 into the furnace it impinges against the flap 25 and will swing such flap in a counter-clockwise direction, as illustrated in Figure 5.

The distance that the flap 25 will be swung will, of course, depend upon the velocity of the air passing through the conduit 8 and the Velocity of the air will be proportionate to the heat of the furnace and the consequent rapidity with which the air in the furnace chamber is being heated to sufficient temperature to pass outwardly through the air pipes 3. As the flap 25 swings under the impingement of the air draft in the conduit 8, the dampers 23 and 24 will swing in unison therewith. The resultant opening movement of the damper 23 will permit a check draft to pass upwardly through the pipe 1 into the flue pipe 4 and the resultant closing of the damper 24 will reduce the volume of air passing into the grate of the furnace.

It will thus be appreciated that as the furnace becomes increasingly hot the velocity of air passing through the conduit 8 will increase which will cause the flap 25 to swing through a greater are with the consequent enlargement of the check draft opening and closure of the grate draft opening, so that the speed of combustion in the furnace will be reduced. As the speed of combustion reduces and the heat in the furnace gradually decreases, the velocity of air passing through the conduit 8 will also decrease with the then proportionate gradual opening of the grate draft damper and proportionate gradual closing of the check draft damper.

In this way the temperature and combustion in the furnace can be retained within close proximity to a predetermined degree, as when the furnace becomes too hot the check draft is gradually opened and the grate draft reduced or cut off, and when the furnace starts to cool down below a predetermined degree with the resultant reduction of air velocity in the conduit 8, the flap will gradually swing back with the resultant gradual closing of the check draft and opening of the grate draft.

In speaking of velocity of the air passing through the conduit 8, it is to be understood that no great velocity of air is required to swing the flap 25 but that the flap will readily swing under the natural slow moving air draft sucked through a hot air furnace.

If it is desired to increase or lessen the sensitivity or responsiveness of my device, the adjustment can be very simply achieved by manipulation of the thumb-screw I5. By rotating the thumb-screw l5 so that the lug I4 on the member II] is moved upwardly and away from the lug l3 on the member 9, the member l0 and its leg 11, in swinging about the pin l2, will be increased in inclination from the vertical, as shown in Figure 4.

It will be understood that as the spindle l9 carrying the flap 25 increases in inclination with the member ID and its leg I1, that the greater the inclination given to the spindle 19 the greater will be the effort or air velocity necessary to swing the flap from its position when at rest. Conversely the closer the spindle I9 is to bein absolutely vertical, the less will be the effort or air velocity required to swing the flap. A very fine adjustment of my device can be secured through movement of the thumb-screw I5. While I have shown my spindle l9 carrying the dampers and the flap, as mounted in an 8 shaped frame which is movable in relation to another 8 shaped frame carried upon the ends of the air draft pipes, it is to be understood that I could mount my device in a number of other ways to secure the same result without departing from the spirit of my invention as set forth in the appended claims.

What I claim as my invention is:

1. In a hot air furnace, the combination with the draft and check dampers and the air heating chamber in the furnace having a cold air inlet, of a horizontally swingable member positioned within the path of the natural flow of air drawn into the furnace air heating chamber and gradually swinging under the impingement of an increasing air flow velocity to gradually move the draft damper towards a fully closed position and the check damper towards a fully open position.

2. A construction as claimed in claim 1, wherein the draft and check dampers and the horizontal swingable member are secured upon a freely swingable slightly tilted vertical spindle.

3. In a hot air furnace, the combination with the draft and check dampers and the air heating chamber in the furnace having a cold air inlet, of a horizontally swingable flap carried on a slightly tilted vertical axis and positioned within the path of the natural flow of air drawn into the furnace air heating chamber and gradually swinging under the impingement of an increasing air flow velocity to gradually move the draft damper towards a fully closed position and the check damper towards a fully open position.

4. In a hot air furnace, the combination with the draft and check dampers and the air heating chamber in the furnace having a cold air inlet, of a horizontally swingable flap carried on a slightly tilted vertical axis and positioned within the path of the natural flow of air drawn into the furnace air heating chamber and gradually swinging under the impingement of an increasing air flow velocity to gradually move the draft damper towards a fully closed position and the check damper towards a fully open position, a

flap are secured.

MILLARD WHYTE BEST. 

